Dynamo-electric machine



July 26, 1938. J. H. BLANKENBUEHLER 2,125,062

Y Numb-ELECTRIC MACHINE Filed June 15, 41935 '2 sheets-sheet 1 TOR" Y July 26, 193s. J. H. BLANKENBUEHLER 2,12'5go62 DYNAMO-ELECTRI C MACHINE Filed June 15, 1955 2 sheets-sheet 2 Il /I/ i hf ATORNEZ Patented `uly 26, 1938 UNITED STATES PATENT OFFICE DYNAMO-ELECTRIC MACHINE of Pennsylvania Application June 15,

32 Claims.

My invention relates, generally, to dynamoelectric machines, and it has particular relation to a dynamo-electric machine of the cross-eld type suitable for use in arc welding and the like,

and which is an improvement over the dynamoelectric machine disclosed in my Patent No. 1,979,665, issued November 6, 1934.

The object of my invention, generally stated, is to provide a dynamo-electric machine which shall be simple and ecient in operation, and which may be readily and economically manufactured.

An important object of my invention is to provide for regulating the output of a cross-eld generator over a wide range of operation.

Another important object of my invention is to provide for stabilizing the operation of a dynamoelectric machine of the cross-field type when it is operating in the low output range.

Still another important object of my invention is to provide for reducing the cost of manufacture of a cross-eld generator by employing parts which require little or no machining.

Another object of my invention is to provide a eld pole having two types of laminations, one

type forming a part of the pole neck and the pole shoe, the other type forming only a part of the pole shoe.

Still another object of my invention is to provide a fulcrum for adjustable magnetic shunt members by means of a special coniiguration of the pole laminations.

Another object of my invention is to provide a magnetic circuit connecting the eld poles of a cross-eld generator comprising a pair of oppositely disposed sets of laminations inside of a cast frame, leach set comprising laminations of substantially the same width and length.

Still another object of my invention is to provide for simultaneously regulating the position of both magnetic shunt members which are disposed on opposite sides of the armature of a cross-field generator for variably bridging the eld poles to correspondingly adjust the output of the generator.

A further object of my invention is to provide for indicating the output capacities of a crossfield generator which correspond to various positions of magnetic shunt members that are employed for regulating its output capacity.

Still another object of my invention is to provide for increasing the reactance of the output circuit of a cross-field generator when the regulating magnetic shunt members are adjusted for operating the machine in the lower output range.

Cil

1935, Serial No. 26,871

Another object of my invention is to provide an auxiliary magnetic shunt member carried by and magnetically insulated from the regulating shunt members of a cross-field generator for reducing the reluctance of the magnetic circuit surrounding one of the eld windings by bridging the eld pole to auxiliary iield poles when the machine is adjusted to operate in the lower output range.

Other objects of my invention will, in part, be obvious and, in part, appear hereinafter.

My invention, accordingly, is disclosed in the embodiment hereof shown in the accompanying drawings, and comprises the features of construction, combination of elements and arrangement of parts, which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description, taken in connection with the accompanying drawings, in which:

Figure l is a View in side elevation of the generator of a motor-generator set, the portion showing the motor being partly broken away since it forms no part of this invention;

Fig. 2 is a sectional view showing the internal construction of the cross-field generator, and in addition, the output circuit connections are also diagrammatically illustrated;

Figs. 3 and 4 are views, respectively, in side and end elevation of an auxiliary pole piece;

Fig. 5 is a sectional view taken along the line V-V of Fig. 2;

Fig. 6 is a plan view of an indicating dial;

Figs. 7 and 8 are views in side elevation of different types of laminations which are used 'to form the main pole pieces; and

Fig. 9 is a perspective view showing the arrangement of the laminations which are used to provide the magnetic circuits between the main eld poles.

Referring now particularly to Fig. 1 of the drawings, the reference character l0 designates, generally, the frame of the generator. The particular construction of the frame I9 and its arrangement in conjunction with the frame for the motor which is employed to drive the generator, are set forth in my Patent No. 2,094,344, issued September 28, 1937, and assigned to the assignee of this application.

As illustrated in Fig. 2 of the drawings, the frame IG is generally circular in shape and it is of cast construction, in order to reduce the cost thereof when it is manufactured in quantity lots. It will be understood, however, that other types of frame construction may be employed such as welded construction. Since the frame Ill is of relatively low magnetic permeability, it is desirable to provide a magnetic circuit inside of it, which will serve as a path for the magnetic flux and have a minimum of reluctance. Furthermore, it is desired to reduce the flow of eddy currents due to rapid flux changes. For these purposes, an inner frame is provided, which comprises two sets of laminations II.

As illustrated in Fig. 9 of the drawings, the laminations II may all be of substantially the same length and Width. It is, therefore, possible to employ standard punchings to make up the sets of laminations II. Although only four laminations are shown, it will be understood that a greater or a lesser number may be employed. For example, in a generator of this type which I have constructed, I have employed eight laminations in each set.

It will be observed in Fig. 2 that the sets of laminations II are oppositely disposed and that they are secured inside of the outer frame IIJ by means of bolts I2, which are positioned in suitably threaded openings in bosses I3 integrally cast with the outer frame Ill. It will also be observed thatthe opposed ends of the sets of the laminations II are stepped, due to the fact that the individual laminations are of the same length and are curved to form an arc of a cylinder when they are positioned within the outer frame Il).

' The generator is provided with main field poles IIB and I which are secured to the outer frame IB by means of bolts I6. It will be observed that the main poles I4 and I5 are positioned in engagement with the stepped ends of the sets of laminations I I, which are positioned between the ends of the poles Il and I5 and bosses I'I which are cast integrally with the outer frame IIJ. Due to the fact that the magnetic iiux flows from the sets of laminations into or out of the main poles I4 and I5, depending upon their polarities, and does not: flow from one of the sets of laminations to the other, it is unnecessary that a complete ring of magnetic structure should be provided inside ofthe outer frame IIl to form the inner frame. Such a construction would be pro-V vided if the laminations forming the sets I I were continuous and formed a continuous ring or spiral. Such a construction, however, would be expensive since laminations of the length required are not feasible or commercially available for standard sizes of generators. Furthermore, it would be necessary to provide openings for the bolts I5, which are unnecessary in the construction which I have provided.

Each of the main poles Ill and I5 has a pole neck I8 and a pole shoe I9. Since the main iiuX of a generator of the cross-field type is present in the pole shoes I9, it is essential that a suitable magnetic circuit be provided having a sufciently low reluctance to permit the required flux to flow. Due to the fact that only a relatively small amount of flux flows through the pole necks I8, it is unnecessary that they be of large cross-sectional area. Furthermore, when a pole neck IB is provided of minimum size, the dimensions of the series eld windings positioned therearound may be considerably reduced. As a result, the cost of the construction is correspondingly reduced.

In order to provide the required cross-sectional area for the various portions of the field poles III and I5, I have provided for constructing them of two types of laminations which are shown in Figs. 7 and 8. In Fig. '7, a lamination 20 is illustrated, which forms only a part of the pole shoe I9. In Fig. 8 a lamination 2I is shown, which forms not only a portion of the pole shoe I9, but also forms the pole neck I8. It will be understood that the field poles are formed by stacking the laminations 20 and 2I the laminations 2I being stacked centrally in the pole, While the laminations 2|] are stacked at the ends thereof. In one modification of a eld pole of this type, I have employed sixty-five laminations of the type shown in Fig. 8, and seventy-eight laminations of the type shown in Fig. 7, thirty-nine of these being disposed on each end of the laminations shown in Fig. 8. In order to hold the laminations in stacked relation, they are provided with punched holes 22, through which rivets may be placed.

The laminations 20 and 2l are provided With cut-out portions 23, in which commutating windings 24 may be positioned. Clips 25, comprising pieces of soft steel, are positioned on the outside laminations 2B of the field poles and are bent around the commutating windings 2li, as illustrated, to hold them in position.

Each of the laminations 20 and 2l has integrally formed therewith on opposite sides, projections 26. These projections are in the same relative location on each of the laminations 20 and 2| so that when they are stacked, they provide a ridge which may be used as a fulcrum for a purpose which will be set forth hereinafter.

As illustrated in Fig. 2 of the drawings, each of the eld poles I4 and I5 is provided with a series iield winding 2'1, which is positioned around the pole neck portion I8 of the field poles. The series eld windings 27, are arranged to be connected in series circuit relation with the commutatingV iield windings 2d, and with the main brushes 28-28, in engagement with a commutatorV 29 of an armature 30, which it will be understood, is positioned between the pole shoes I9 of the eld poles Ill and I5. The commutator 29 is also provided with auxiliary brushes 3|, which may be short circuited in accordance with the usual practice in the construction of a crosseld generator.

In order to reverse the polarity of the generator, a reversing switch, shown generally at 33, is provided and is mounted on the outer frame I0. The reversing switch 33 may be operated by means of a handle 34 which is positioned outside of the frame I0. On operation of the reversing switch 33, the polarity which is applied to the terminals 35 may be reversed. The detailed construction ofthe reversing switch 33 is set forth in my copending application Serial No. 26,872, filed of even date herewith, and assigned to the assignee of this application.

As set forth hereinbefore, the reversing switch 33 is employed to reverse the polarity of the output circuit of the generator. For the purposes of illustration, the output circuit of the generator will be traced in detail as follows. Beginning at the reversing switch 33, the output circuit extends through conductor 36, the series eld winding 2 on the field pole ill, conductor 38, the commutating field winding 24 in the upper field pole Il, conductor 39, main brush 28, commutator 29, armature 30, commutator 29, main brush 28, conductor 4D, the commutating field Winding 24 in the lower main pole I5, conductor 4I, the series eld winding 2'I positioned on the lower main field pole I5 and conductor 42, back to the reversing switch 33.

In order to regulate the output of the generator, a pair of magnetic shunt members 44 is provided for bridging the pole shoes I9 of the field poles I4 and I5. As set forth in my aforesaid patent, the shunt members 44 serve to regulate the armature reaction flux, and in this manner, control the output of the generator. As illustrated, the shunt members 44 are provided with grooves 45 which are arranged to be positioned on the ridges formed by the projections 26 in the pole shoes I9 of the lower pole I5. The ridges formed by the projections 26 thus form a fulcrum or axis about which the shunt members 44 may turn. The shunt members 44 may be provided with a number of short circuited turns 46 for the prupose set forth in my aforesaid patent.

In order to retain the shunt members 44 in position, bolts 41 are provided which are mounted in suitable threaded openings in the pole shoe I9 of the lower pole I5, and which extend through suitable openings in the outer frame I0. Springs 48 are provided, as shown, for normally biasing the shunt members 44 toward the field poles I4 and l5. For the purposes of more clearly illustrating the invention, the shunt members 44 are shown as having considerable clearance between the sides of the pole shoes I9. However, it is actually desired to reduce this clearance to a minimum, in order to permit the generator to operate at the lowest output capacity.

Each of the shunt members 44 is provided with an operating arm 49 having a channel section terminating in a forked end 50', Fig. 5, in which nuts 5I are positioned. The nuts 5I are mounted on a rotatable shaft 52 which is mounted in suitable bearings 53 and 54 in the outer frame Ill. A handwheel 55 is provided for rotating the shaft 52. The nuts 5I are oppositely threaded and are arranged to be moved either away from or toward each other on rotation of the shaft 52 by means of oppositely cut threads on the ends thereof. Thus, when the handwheel 55 is rotated in one direction, the nuts 5I are caused to approach each other, thereby permitting the shunt members 44 to be urged toward each other under the influence of the biasing springs 48. When the handwheel 55 is rotated in the other direction, the nuts 5I are simultaneously moved away from each other and the shunt members 44 are moved simultaneously away from the pole shoes I9. In order to limit the movement of the nuts 5I toward each other and to prevent their coming out of the forked ends 50, a sleeve 56 is provided around the shaft 52.

Since there is a denite relation between the output capacity of the generator and the position of the shunt members 44, it is unnecessary to provide a meter, such as an ammeter of the moving coil type, to indicate the current that is flowing. Instead, advantage may be taken of this relationship and a corresponding indication may be given as to the output setting of the machine whether it is in operation or not. For this purpose, a pinion 59 is mounted on the shaft 52 and is arranged to rotate therewith. As illustrated in Fig. 5 of the drawings, the pinion 59 is disposed to engage a dial 60, Fig. 6, which is provided with teeth in the periphery thereof. The dial 60 is mounted for rotation inside of the outer frame I0 and has provided thereon two scales BI and 62, indicating the output rating of the generator for different positions of the shunt members 44. The Scale l6I indicates the current output of the generator when the output voltage, for example the voltage across a welding arc, is maintained at 20 volts. The scale 92 provides a corresponding indication when the voltage across the load circuit is 40 volts. In order to View the dial 60, a window 63 is provided in the outer frame ID, as illustrated. As shown, the window 63 is provided in the outer frame Il] with suitable indexes corresponding to the different voltage ratings for the two scales 6I and 62.

In the lower output range of the generator, it is desirable to further increase the reactance of the output circuit, in order to stabilize the operation of the generator at the low currents. For this purpose, I have provided auxiliary pole pieces B5, which are secured to the outer frame I0 by means of bolts 66, and which project inwardly therefrom toward the upper eld pole I4, as illustrated in Fig. 2 of the drawings. As shown in Fig. 3 of the drawings, the auxiliary poles 65 may be provided with cut away sections 61 to permit their being positioned around the sets of laminations I I and to be firmly secured to the outer frame I0.

With a view to providing a more complete magnetic circuit around the series field winding 27 in the low output range, each of the shunt members 44 is provided with an auxiliary maghet shunt member 68, which is secured thereto and which may be magnetically insulated therefrom by means of support members 69 of nonmagnetic material, such as brass. Screws "I9, Fig. 5, are provided for securing the support members '69 to the shunt member 44 and the auxiliary shunt members 68. The auxiliary shunt members 68 may be provided with slots 'II to permit them to be moved into close proximity to the pole shoe of the upper eld pole I4, the slots II registering with the ridges formed on the upper pole I4 by the projections 26.

It will be readily understood that a complete magnetic circuit having low reluctance will be provided around the series eld winding 2'I that is mounted on the upper field pole I4 when the shunt members 44 are positioned in close proximity to the pole shoes I9. When they are moved, for example, to a position which may be illustrated by the dotted lines shown in connection with the shunt member 44 on the right-hand side of the armature 30, the reluctance of the foregoing circuit will be considerably increased, due to the movement of the auxiliary shunt members 68 away from bridging relation between the auxiliary poles 65 and the pole shoe I9 of the upper field pole I4. Furthermore, when the auxiliary shunt members 68 are moved out of bridging relation as set forth, the maximum output capacity of the generator is increased since there is less leakage flux around the series eld winding 2'I positioned on the upper field pole I4 than would otherwise be the case.

Since certain further changes may be made in the foregoing construction and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter set forth in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A dynamo-electric machine of the crossfield type comprising, in combination, an outer frame of cast construction, an inner frame forming a part of the magnetic circuit for the machine including a plurality of laminations having the width thereof .disposed substantially parallel to the inner wall of said outer frame vand secured thereto; a Apair of iield poles secured to and projecting inwardly from-said outer frame to form an additional part of the magnetic circuit of the machine with said laminations, each of said field poles including a plurality of laminations disposed to be stacked to form the pole neck and a portion of the pole shoe, and a plurality of additional laminations disposed to be stacked with said last-named laminations to form the remaining portion of the pole shoe; a series eld winding disposed around the pole neck of each of said eld poles, an armature having a pair of main brushes connected to said series field windings and a pair of short circuited auxiliary brushes disposed between said field poles, movable magnetic shunt means disposed to b-ridge said eld poles, adjusting means for variably positioning saidmagnetic shunt means to change the output of the machine, indicating means positioned within said outer frame and operatively connected to said adjusting means for indicating the output capacity of the machine corresponding to the position of said magnetic shunt means, and a window in said outer frame to permit inspection of said indicating means.

2. A dynamo-electric machine of the crosseld type comprising, in combination, an outer frame of cast construction, an inner frame forming a part of the magnetic circuit for the machine including a plurality of laminations having the Width thereof disposed substantially parallel to the inner wall of said outer frame and secured thereto; a pair of eld poles secured to and projecting inwardly from said outer frame to form an additional part of the magnetic circuit of the machine with said laminations, each of said eld poles including a plurality of laminations disposedto be stacked to form the pole neck and a portion of the pole shoe, and a plurality of additional laminations disposed to be stacked with said last-named laminations to form the remaining portion of the pole shoe; a series eld winding disposed around the pole neck of each of said i'leld poles, an armature having a pair of main brushes connected to said Series field windings and a pair of short circuited auxiliary brushes disposed between said field poles, a pair of magnetic shunt members hinged to opposite sides of one of said eld poles and disposed to variably bridge them, adjusting means including a rotatable shaft operatively connected to said shunt members for simultaneously moving them away from or toward said eld poles to correspondingly increase or decrease the output of the machine, a pinion disposed to rotate with said shaft, a dial rotatably mounted within said outer frame and provided with teeth in the periphery thereof disposed to engage said pinion, a scale on said dial for indicating the output capacity ofthe machine corresponding to the position of said shunt members, and a window in said outer frame for observing said scale.

3. A `dynamo-electric machine of the crosseld type comprising, in combination, an outer frame of cast construction, an inner frame forming a part of the magnetic circuit for the machine including a plurality of laminations having the Width thereof disposed substantially parallel to the inner wall of said outer frame and secured theretorapair, of field poles secured to and Yprojecting inwardly from said router frame to form an additional part'oi the magnetic circuit of the machine withsaid-laminations, each of said field poles including a plurality'of laminations disposed to be stacked to form the pole neck and a portion of the pole shoe, and a plurality of additional laminations disposed to be stacked with said last-named laminations to form the remaining portion of the pole shoe; a series eldwinding disposed around the pole neckofreach of said eld poles, an armature having a pair of main brushes connected to said series eld windings and a pair of short circuited auxiliary brushes disposed between said field poles, a pair of magnetic shunt members hinged to opposite sides of one of said eld poles and disposed to variably bridge them, adjusting means including a rotatable shaft operatively connected to said shunt members for simultaneously moving them away from or toward said iield poles to correspondingly increase or decrease the output of the machine, a pair of auxiliary poles carried by said outer rame, said auxiliary poles being positioned on opposite sides of and extending toward said other field pole and disposed to cooperate with said shunt members on operation thereof to positions corresponding to low output settings of the machine for decreasing the reluctance of the magnetic circuitV associated With the iield winding on said other field pole at said settings, a pinion disposed to rotate with said shaft, a dial rotatably mounted within said outer frame and provided with teeth in the periphery thereof disposed to engage said pinion, a scale on said dial for indicating the output capacity of the machine corresponding to the position of said shunt members, and a window in said outer frame for observing said scale.

4. A dynamo-electric machine of the cross-field type comprising, in combination, an outer frame of cast construction, an inner frame forming a part of the magnetic circuit for the machine including a plurality of laminations having the width thereof disposed substantially parallel to the inner wall of said outer frame and secured thereto;Y a pair of eld poles secured to and projecting inwardly from said outer frame to form an additional part of the magnetic circuit of the machine with said laminations, each of said eld poles including a plurality of laminations disposed to be stacked to form the pole neck and a portion of the pole shoe, and a plurality of additional laminations disposed to be stacked with said last-named laminations to form the remaining portion of the pole shoe; a series eld winding disposed around the pole neck of each of said field poles, an armature having a pair of main brushes connected to said series eld windings and a pair of short circuited auxiliary brushes disposed between said eld poles, a pair of magnetic shunt members hinged on opposite sides to one of said Vfield poles and disposed to bridge them, adjusting means including a rotatable shaft operatively connected to said shunt members for simultaneously moving them to change the output of the machine, a pair of auxiliary poles carried by said outer frame, said auxiliary poles being positioned on opposite sides of and extending toward said other field pole, an auxiliary magnetic shunt member carried by and magnetically insulated from each of said shunt members and disposed to cooperate with said auxiliary poles and said other field pole on operation of said shunt members to positions corresponding to low output settings of the machine to increase the inductance of the output circuit of the machine at said low current settings, a pinion disposed to rotate with said shaft, a dial rotatably mounted within said outer frame and provided with teeth in the periphery thereof disposed to engage said pinion, a scale on said dial for indicating the output capacity of the machine corresponding to the position of said magnetic shunt members, and a window in said outer frame for observing said scale.

5. A dynamo-electric machine of the cross-field type comprising, in combination, an outer frame of cast construction, an inner frame comprising two sets of oppositely disposed laminations secured to said outer frame, all of said laminations being of substantially the same length and the width thereof being disposed substantially parallel to the longitudinal axis of said outer frame; a pair of field poles secured to said outer frame in engagement with the ends of said sets of lamination and projecting inwardly, each of said field poles including a plurality of pole laminations disposed to be centrally stacked to form the pole neck and a portion of the pole shoe, and a plurality of additional pole laminations disposed to be stacked at each end of the eld pole and forming the balance of the pole shoe, each of said pole laminations having integrally formed therewith single projections in the pole shoe portion on opposite sides thereof to provide ridges; a series eld winding disposed around the pole neck of each of said eld poles, an armature having a pair of main brushes connected to said series field windings and a pair of short circuited auxiliary brushes disposed between said eld poles, a pair of movable magnetic shunt members fulcrumed on the ridges of one of said eld poles and disposed to bridge said field poles, adjusting means for variably positioning said magnetic shunt members to change the output of the machine, indicating means positioned within said outer frame and operatively connected to said adjusting means for indicating the output capacity of the machine corresponding to the position of said magnetic shunt means, and a window in said outer frame to permit inspection of said indicating means.

6. A dynamo-electric machine of the cross-field type comprising, in combination, an outer frame of cast construction, an inner frame comprising two sets of oppositely disposed laminations secured to said outer frame, all of said laminations being of substantially the same length and the width thereof being disposed substantially parallel to the longitudinal axis of said outer frame; a pair of eld poles secured to said outer frame in engagement with the ends of said sets of lamination and projecting inwardly, each of said field poles including a plurality of pole laminations disposed to be centrally stacked to form the pole neck and a portion of the pole shoe, and a plurality of additional pole laminations disposed to be stacked at each end of the field pole and forming the balance of the pole shoe, each of said pole laminations having integrally formed therewith single projections in the pole shoe portion on opposite sides thereof to provide ridges; a series field winding disposed around the pole neck of each of said eld poles, an armature having a pair of main brushes connected to said series eld windings and a pail 0f ShOrt CTCllted auxiliary brushes disposed between said field poles, a pair of movable magnetic shunt members fulcrumed on the ridges of one of said eld poles and disposed to bridge said field poles, adjusting means including a rotatable shaft operatively connected to said shunt members for simultaneously moving them away from or toward said field poles to correspondingly increase or decrease the output of the machine, a pinion disposed to rotate with said shaft, a dial rotatably mounted within said outer frame and provided with teeth in the periphery thereof disposed to engage said pinion, a scale on said dial for indicating the output capacity of the machine corresponding to the position of said shunt members, and a window in said outer frame for observing said scale.

7. A dynamo-electric machine of the cross-field type comprising, in combination, an outer frame of cast construction, an inner frame comprising two sets of oppositely disposed laminations secured to said outer frame, all of said laminations being of substantially the same length and the width thereof being disposed substantially parallel to the longitudinal axis of said outer frame; a pair of field poles secured to said outer frame in engagement with the ends of said sets of lamination and projecting inwardly, each of said field poles including a plurality of pole laminations disposed to be centrally stacked to form the pole neck and a portion of the pole shoe, and a plurality of additional pole laminations disposed to be stacked at each end of the field pole and forming the balance of the pole shoe, each of said pole laminations having integrally formed therewith single projections in the pole shoe portion on opposite sides thereof to provide ridges; a series field winding disposed around the pole neck of each of said eld poles, an armature having a Pair of main brushes connected to said series eld windings and a pair of short circuited auxiliary brushes disposed between said eld poles, a pair of movable magnetic shunt members fulcrumed on the ridges of one of said eld poles and disposed to bridge said field poles, adjusting means including a rotatable shaft operatively connected to said shunt members for simultaneously moving them away from or toward said iield poles to correspondingly increase or decrease the output of the machine, a pair of auxiliary poles carried by said outer frame, said auxiliary poles being positioned on opposite sides of and extending toward said other field pole and disposed to cooperate with said shunt members on operation thereof to positions corresponding to low output settings for the machine for decreasing the reluctance of the magnetic circuit associated with the field winding on said other eld pole at said settings, a pinion disposed to rotate with said shaft, a dial rotatably mounted within said outer frame and provided with teeth in the periphery thereof disposed to engage said pinion, a scale on said dial for indicating the output capacity of the machine corresponding to the position of said shunt members, and a window in said outer frame for observing said scale.

8. A dynamo-electric machine of the cross-field type comprising, in combination, an outer frame of cast construction, an inner frame comprising two sets of oppositely disposed laminations secured to said outer frame, all of said laminations being of substantially the saine length and the width thereof being disposed substantially parallel toi the longitudinal axis of said outer frame; a pair of field poles secured to said outer frame in engagement with the ends of said sets of lamination and projecting inwardly, each of said eld poles including a plurality of pole laminations disposed to be centrally stacked to form the pole neck and a portion of the pole'shoe, and a plu'- rality of additional pole laminations disposed to be stacked at each end of the eld pole and forming the balance of the pole shoe, each of said pole laminations having integrally formed therewith single projections in the'pole shoe portion on opposite sides thereof to provide ridges; a vseries field winding disposed around the pole neck of each of said field poles, an armature having a pair of main brushes connected to said series field windings and a pairof short circuited auxiliary brushes disposed between said field poles, a pair of movable magnetic shunt members fulcrumed'on the ridges. of one of said field poles and disposed to bridge said field poles, adjusting means'including a rotatable shaft operatively connected to said shunt members for simultaneously moving them away from or toward said eld poles to correspondingly increase or decrease the output of the machine, a pair of auxiliary poles carried by said outer frame, said auxiliary poles being positioned on opposite sides of and extending toward said other iield pole, an auxiliary magnetic shunt member carried by and magnetically insulated'from each of said shunt members and disposed to cooperate with said auxiliary poles and said other eld pole on operation of said shunt members to positions corresponding to low output settings for the machine to increase the inductance of the output circuit of the machineV at said low current settings, a pinion disposed to rotate with said shaft', a dial rotatably mounted within said outer frame and provided withteeth in the periphery thereof disposed toV engage said pinion, a scale on said dial for indicating the output capacity of the machine corresponding to the position of said shunt members, anda window in said outer frame for observing said scale.

9.A eld pole for a dynamo-electric machine comprising, in combination, a plurality of lami- Ynations. disposed to be contiguously stacked to form the pole neck and a portion of the pole shoe, "and a plurality of additional laminations disposed to be contiguously stacked with said rstmentioned laminations and forming the remaining portion of the pole shoe;

10. A field pole for a dynamo-electric machine comprising, in combination, a plurality of laminations disposed to Ybe solidly stacked to form the pole neck and the central portion of the pole shoe, and a plurality of additional laminations disposed to be stacked adjacent to said firstmentioned stack of laminations to increase the length of the pole shoe, said laminations having integrally formed projections to provide a fulcrum for a movable shunting member.

11. A eld pole for a dynamo-electric machine comprising, in combination, a plurality oi laminations disposed to be centrally stacked in the pole and forming the pole neck and a portion of the pole shoe, and a plurality of additional laminations disposed to be stacked at each end of the eld pole and forming the remainder of the pole shoe.

12. A eld pole for a dynamo-electric machine comprising, in combination, a plurality of laminations disposed to be centrally stacked in the pole and forming the pole neck and a portion of the pole shoe, and a plurality of additional laminations disposed to be stacked at each end of the field pole and forming the remainder of the pole shoe, each of said laminations Vhaving integrally formed therewith a projection in the pole shoe portion in the same relative position as on the other laminations to providea iulcrum for a movable shunting member.

13. A field pole for a dynamo-electric machine comprising, in combination, a plurality of laminations disposed to be centrally stacked in the pole, each of said laminations having a pole neck portion and a pole shoe portion, a plurality of additional laminations disposed to be stacked at each end of the field pole, the entire portion of each of said additional laminations corresponding to the pole shoe portions of said firstmentioned laminations, and means for securing said laminations in stacked relation.

14. A field pole for a dynamo-electric machine comprising, in combination, a plurality of laminations disposed to be centrally stacked in the pole, each of said laminations having a pole neck portion and a pole shoe portion, a plurality of additional laminations disposed to be stacked at each end of the eld pole, the entire portion of each of said additional laminations corresponding to the pole shoe portion of said firstmentioned laminations, and'means for securing said laminations in stacked relation,the pole shoe portion oi each of said laminations being provided with an integrally formed projection on the opposite'ends thereof in the same relative position on all of said laminations to provide fulcrums for movable shunting members.

15. A frame vfor a dynamo-electric machine comprising, in combination, an outer frame disposed to support the eld structure of thermachine, and an inner magnetic circuit for the machine, said inner magnetic circuit comprising two oppositely disposed sets'of laminations secured within the outer frame'independently oi said field structure, all of said laminations being of substantially Vthe same length and the width thereof being disposed substantially parallel to the longitudinal axis of said outer frame'.

16. In a magnetic circuit for a dynamo-electric machine, a plurality of oppositely disposed sets of substantially identical rectangular laminations stacked to substantially form an arc of a cylinder thereby causing at least one end of said laminations to be stepped, said sets of laminations being secured within a iield member supporting' structure independently of said field members,

17. A dynamo-electric machine of the crossfleld type comprising, in combination, a pair of eld poles having integral projections thereon, an armature having main and auxiliary brushes disposed between said field poles, a pair of magnetic' shunts resiliently maintained in engagement with opposite sides of one of said eld poles for variably bridging them, said resilient means biasing said magnetic shunts toward the' other of said field poles, and adjusting means comprising a single threadedrod operatively connected to said shunts for simultaneously moving them away from said eld poles against the biasing force of said resilient means to increase the output of the machine.

18. A dynamo-electric machine of the crossiield type comprising?, in combination, a frame, a pair of iield poles carried by said frame, an armature having main and auxiliary brushes disposed between said field poles, movable mag'- netic shunt means disposed to bridge said field poles, adjusting means for variably positioning said magnetic shunt means to change the output of the machine, and auxiliary pole means carried by said frame, said auxiliary pole means extending toward one ofV said field poles and Iis disposed to cooperate with said magnetic shunt means on operation thereof to positions corresponding to low output settings for the machine.

19. A dynamo-electric machine of the crosseld type comprising, in combination, a frame, a pair of eld poles carried by said frame, an armature having main` and auxiliary brushes disposed between said field poles, a magnetic shunt member hinged to one of said eld poles and disposed to bridge them, adjusting means for variably positioning said shunt member to change the output of the machine, and an auxiliary pole carried by said frame, said auxiliary pole extending toward the other of said field poles and disposed'to cooperate with said shunt ymember on operation thereof to positions corresponding to low output settings for the machine.

20. A dynamo-electric machine of the crosseld type comprising, in combination, a frame, a pair of field poles carried by said frame, an armature having main and auxiliary brushes disposed between said eld poles, a pair of magnetic shunt members hinged to one of said field poles and disposed to bridge them, adjusting means for variably positioning said shunt members to change the output of the machine, and a pair of auxiliary poles carried by said frame, said auxiliary poles being positioned on opposite sides of and extending toward said other eld pole and disposed to cooperate with said shunt members on operation thereof to positions corresponding to low output settings for the machine.

21. A dynamo-electric machine of the crossfield type comprising, in combination, a frame, a pair of field poles carried by said frame, an armature having main and auxiliary brushes disposed between said eld poles, movable magnetic shunt means disposed to bridge said eld poles, adjusting means for variably positioning said magnetic shunt means to change the output of the machine, auxiliary pole means carried by said frame and extending toward one of said eld poles, and additional magnetic shunt means carried by and magnetically insulated from said first-mentioned shunt means and disposed to cooperate with said auxiliary pole means on operation of said first-mentioned shunt means to positions corresponding to low output settings for the machine to increase the inductance of the output circuit of the machine.

22. A dynamo-electric machine of the crossfield type comprising, in combination, a frame, a pair of eld poles carried by said frame, an armature having main and auxiliary brushes disposed between said eld poles, a magnetic shunt member hinged to one of said eld poles and disposed to bridge them, adjusting means for variably positioning said shunt member to change the output of the machine, an auxiliary pole carried by said frame and extending toward the other of said iield poles, and an auxiliary magnetic shunt member carried by and magnetically insulated from said shunt member and disposed to cooperate with said auxiliary pole and said other eld pole on operation of said shunt member to positions corresponding to low output settings for the machine to increase the inductance of the output circuit of the machine.

23. A dynamo-electric machine of the crosseld type comprising, in combination, a frame, a pair of eld poles carried by said frame, an armature having main and auxiliary brushes disposed between said eld poles, a pair of magnetic shunt members hinged to one of said field poles and disposed to bridge them, adjusting means for variably positioning said shunt members to change the output of the machine, a pair of auxiliary poles carried by said frame, said auxiliary poles being positioned on opposite sides of and extending toward said other iield pole, and an auxiliary magnetic shunt member carried by and magnetically insulated from each of said shunt members and disposed to cooperate with said auxiliary poles and said other iield pole on operation of said shunt members to positions corresponding to low output settings for the machine to increase the inductance of the output circuit of the machine.

24. In a dynamo-electric machine of the crosseld type having a pair of eld poles and an armature interposed therebetween the combination of an integral ridged projection on a side of at least one field pole, a magnetic shunt resiliently positioned in engagement with a ridged projection of a field pole on one side of said armature for Varying the reaction iiux thereof, and means for adjusting said shunt.

`25. In a dynamo-electric machine of the crosseld type having a pair of field poles and an armature interposed therebetween the combination of field poles having integral ridged projections, a pair of magnetic shunts resiliently retained in pivotal engagement with said projections on opposite sides of a field pole, and a single adjusting means comprising a threaded shaft operatively connected to an end of each of said shunts for simultaneously moving said end toward or away from a eld pole to correspondingly decrease or increase the output of the machine.

26. A magnetic structure for a dynamo-electric machine comprising, in combination, an outer supporting frame, a plurality of field pole members secured to and projecting inwardly from said outer frame, and an inner main magnetic circuit comprising separate sets of similar laminations disposed between adjacent eld pole members and independently secured to said outer frame, the width of said laminations being essentially parallel to the axis of said machine, and adjacent ends of successive sets of laminations being separated from one another.

27. A structure for a dynamo-electric machine comprising, in combination, an outer frame member, a plurality of field pole members each comprising a plurality of laminations stacked to form a pole neck and a pole shoe and a plurality of additional laminations stacked adjacent to the first-mentioned stack to increase the face area of said pole shoe, said eld pole members being secured to said outer frame, and an inner magnetic circuit comprising sets of similar rectangular laminations independently secured within the outer frame with the width of a lamination being essentially parallel to the axis of the machine, and the length of a lamination being in arcuate relation between a pair of adjacent eld pole members.

28. The combination in a structure for a dynamo-electric machine comprising a rigid supporting frame, a plurality of field pole members supported by said frame, and a magnetic circuit comprising separate sets of substantially identical laminations disposed to be secured within the supporting frame in arcuate relation between adjacent iield pole members, adjacent ends of successive sets of laminations being clamped in spaced relation between a eld pole member and said frame.

29. A dynamo-electric machine of the crossfield type, comprising, in combination, a frame, a 75 pair of main field poles, an armature with main and auxiliary brushes, and adjustable means in shunt With one of said main' field poles and said frame for varying the reluctance of the path of the leakage uX between a main pole and the frame to control the output of the machine.

30. A-dynamo-electric machine of the crosseld type, comprising, in combination, a frame, a pair of main eld poles, an armature With main and auxiliary brushes, a movable member disposed in shunt relation with one of the main field poles and the frame operable to vary the reluctance of the leakage ux path between said main field pole and said frame to control the output of the machine, and means for adjusting the position of the movable member.

31. A dynamo-electric machine of the crossfield type, comprising, in combination, a frame, a pair of main field poles, an armature with main and auxiliary brushes, adjustable means in shunt With a main field pole and the frame operable to Vary the output of the machine by varying the reluctance of the leakage iiux path between the main field pole and frame, means including a rotatably mounted shaft for actuating the adjustable means, and indicating means actuated by said shaft for indicating the output of the machine in accordance with the position of said adjustable means.

32. A direct-current generator of the crossfield type, comprising, in combination, a frame, a pair of main field poles secured within the frame opposite one another, an armature rotatably mounted coaxally with the frame having main and auxiliary brushes, movably mounted means in shunt with one of the main field poles and frame for controlling the output of the generator by varying the reluctance 0i` the leakage flux path between the main field pole and the framle, means for actuating the movably mounted means to dierent positions, and an indicating dial actuated by said means for indicating the output of the generator in accordance with the position of the movably mounted means.

JOHN H. BLANKENBUEI-ILER. 

